Refine error codes throughout the upgrader so we can better detect at what stage updates fail.

see #22704.


git-svn-id: http://develop.svn.wordpress.org/trunk@25763 602fd350-edb4-49c9-b593-d223f7449a82
Silence possible warnings from is_dir(). fixes #25572.


git-svn-id: http://develop.svn.wordpress.org/trunk@25764 602fd350-edb4-49c9-b593-d223f7449a82
Twenty Fourteen: remove header text customization options, fixes #25540. Props celloexpressions, obenland.

git-svn-id: http://develop.svn.wordpress.org/trunk@25765 602fd350-edb4-49c9-b593-d223f7449a82
Twenty Fourteen: remove unneeded sidebar file. Props iamtakashi, see #25565.


git-svn-id: http://develop.svn.wordpress.org/trunk@25766 602fd350-edb4-49c9-b593-d223f7449a82
Update the basic browser detection to detect IE11. Fixes #25562.

git-svn-id: http://develop.svn.wordpress.org/trunk@25767 602fd350-edb4-49c9-b593-d223f7449a82
Twenty Fourteen: remove two unused files, should have been deleted with r25088, see #24877.


git-svn-id: http://develop.svn.wordpress.org/trunk@25768 602fd350-edb4-49c9-b593-d223f7449a82
Twenty Fourteen: first pass for updating code comments to reflect WP inline docs standards, see #25257.

git-svn-id: http://develop.svn.wordpress.org/trunk@25769 602fd350-edb4-49c9-b593-d223f7449a82
Add explicit link to the installation being updated in debugging emails. see #22704.


git-svn-id: http://develop.svn.wordpress.org/trunk@25770 602fd350-edb4-49c9-b593-d223f7449a82
Fix typo in wp-admin.css. props wycks. fixes #25589.

git-svn-id: http://develop.svn.wordpress.org/trunk@25771 602fd350-edb4-49c9-b593-d223f7449a82